Electrical switch of the tumbler type



Feb. 6, 1934- J. A. CRABTREE ELECTRICAL SWITCH OF THE TUMBLER TYPE 2 Sheets-Sheet 1 Filed Feb. 10, 1932 [Mil/09770 Feb. 6, 1934. J. A. CRABTREE 1,946,192

ELECTRICAL SWITCH OF THE TUMBLER TYPE Filed Feb. 10, 1932 2 SheetsSheet 2 Ratented Feb. 6, 1934 P T T John Ashworth Crabtree, Sutton Coldfield, England Application February 10, 932,

and in Great Britain February '7 (liaims.

My invention has reference to snap-action electrical switches of the tumbler type in which a toggle connection between the tumbler and the rocking contact arm is made by a floating spring link, and a positive starting displacement or" the said rocker-arm is obtained by the levering of the said link against a fulcrum attachment on the base of the switch.

My said invention is directed to the problem of providing a compact and inexpensive but efficient positive-action switch mechanism capable of accommodation in a switch-base of small diameter and relatively shallow depth, and with this object in view, the abutment member comprises a flat or substantially flat or plate-like portion which is pierced with an aperture so shaped as to provide oscillating clearance for, and the posi-- tive-start fulcra for, the floating toggle-link. The rocker arm is suspended from a fixed pivot pin arranged in spaced or elevated relation to the fulcra of the abutment member, and the spring of the floating link is so confined as to enable the portion of the said link adjacent its connection with the operating tumbler to lever directly upon the fulcrum or fulcra ofthe said abutment member.

In the accompanying drawings, I show, by way of example, a switch constructed in accordance with an application of my invention. I

In the drawings,

Figures 1 and 2 are sections taken respectively on the dotted lines l-1, of Figure 2, and 2-2 of Figure 1, and

Figure 3 is a plan of the combined abutment and rocker-stop member, and Figures 4 to 7 are diagrams explanatory of the operations of the mechanism.

In this switch, the abutment member a is a flat or plate-like sheet-metal pressing, pierced with an H-shaped aperture 1) which presents a pair of parallel clearances c c for the sides (2 d of the rocker arm, and two intermediate tongues e 6 whose ends constitute the positive-start fulcra for the floating toggle link 1. The said member is disposed across the rocker-arm run-way g (see Figure 2) and the fulcrum ends of the tongues c e are sufilciently separated to provide worlnng clearance between them for the said link 7. The rocker-arm clearances are or" such dimensions, and. the member itself is disposed in such relation to the suspension-pin d of the rocker-arm, that the parts of the said member occurring at the opposite ends c c of the said clearances constitute the steps against which the rocker-arm Serial No. 592,127,

sides impinge on completion of its spring-driven make or break movement.

The rocker suspension-pin d (which also serves as the pivot for the tumbler h) is arranged in spaced or elevated relation to the aperture 1) or the member a and is disposed in the plane of the clearance e between the fulcrum ends of the tongues e. The extent to which the suspension pin is thus spaced or elevated from the member a, and the dimensions of the rocker-arm clearances c, are the factors which determine the amplitude of oscillation of the rocker arm and may be varied as desired consistent with an adequate break movement or the said rocker being provided for. Preferably, however, and as in the switch illustrated, the suspension pin is so located that the desired angle of rocker oscillation can be afiorded by relatively short clearances e, such as can be contained in a plate which is of compact dimensions, but nevertheless possesses the necessary inherent strength and rigidity to enable the same to withstand the positive-action stresses and to function effectively as a rocker-arm stop.

The suspensiompin al may be secured in its spaced or elevated relationship to the abutment member in any convenient manner, but preferably and as in the sw bled by utilizing the screws 2' that also fix the abutment member to the base, and by employing pin-elevating or spacing washers 9' of suitable thickness which are strung upon the screws 72 and are interposed between the ends of the suspension pin and the abutment member.

The floating link f is a flat one-piece pressing, whose one end f slidably engages a spring thrust-piece i which is trunnioned to the rockerarin, whilst the other and wider part is pivotally connected at f to the tumbler of the switch. A compression spring f surrounding the link is interposed between the trunnioned thrust-piece f and abutment shoulders at i which are so disposed as to confine the spring to the part of the link remote from the tumbler end and to leave the other part of the said link (i. e. the widened part adjacent the tumbler connection) clear of any spring coils so that this part may directly engage with and lever upon one or other of the fulcrum tongues of the abutment member a for positively starting the rocker-arm during the initial operation of the tumbler.

The extent to which the inner ends of the said fulcrum tongues are separated and the location of the pivot-pin d in relation tothe abutment member are the factors that mainly govern the timing of the positive action in relation to the itch illustrated, it is assem- V completion of the stressing of the snap-spring and the passing of the spring-pin and tumbler joint over dead-centre.

In the switch illustrated, the arrangement provides not only for the positive starting of the rocker-arm but also (as in the event of the spring failing to complete the rocker stroke) for the completion of the said stroke by a positive action obtained from the same fulcrum.

The moving parts are, by the spring-thrust on the toggle system, postioned as shown in Figure 1, when the switch is closed. By the initial spring-stressing displacement of the tumbler in the switch-opening direction, the floating link is moved into contact with the abutment e and is constructed to lever thereon as a fulcrum for positively starting the stroke or" the rocker. At the commencement of this positive action, the head of the link levers on an edge or surface of the abutment-tongue remote from the pivotal centre of the link as shown in Figure 4, and then continues to lever as shown in Figure 5 until the toggle has been carried beyond dead centre as shown in Figure 6. Normally the spring f will then come into action to snap the rocker into the off position as shown in dotted lines in the said Figure 6, but if for any reason the spring fails and is prevented from performing this func tion, then by continuing the manual displacement of the tumbler, the floating link may be taken again into contact with the same abutment e but on the edge or surface nearest the centre of the said link, and be constrained to lever thereon (as shown in Figure 7) to complete the break movement of the rocker. In the next closing operation of the switch, the reverse operations obtain, or are obtainable, by the levering of the link on the other abutment tongue e.

The fulcrum ends of the abutments e e may, however, so be spaced and disposed, and the piv otal centre of the tumbler floating link and contact rocker may so be selected and arranged that, during each normal operation of the switch, the

said floating link is made to contact with a fulcrum surface, during its movement under spring action. That is to say, the link may be made so to contact before its normal spring-driven displacement is completed, so that its final movement is obtained by spring action assisted or supplemented by the positive action obtained by the levering of the said link on a stationary abutment. In such a system, the contact rocker may still, by manual actuation of the tumbler, be displaced positively throughout its entire stroke in either direction should the spring fail or be prevented from acting normally.

In a case where positive action in one direction only has to be provided for, the aperture in the abutment member may be formed with a single fulcrum tongue against which the toggle-link levers either at the start of the opening operation, or of the closing operation, according to the position in which the said single fulcrum is located.

Having described my invention, what I claim and desire to secure by Letters Patent is:--

1. A switch of the class described, comprising a base, an operating-tumbler, a. rocking contact arm pivoted in relation to the said base, a floating link pivotally interposed between the tumbler and contact arm, a positive-start abutment member fixed on the base, a spring-thrust member pivoted to the contact-arm and slidably engaged by the link, a spring thrust on the link, and a spring inter-posed between the said thrusts, the thrust on the link being so disposed as to confine the spring to the part of the link remote from the operating tumbler, to permit of the head of the said link levering directly upon the positive-start abutment member.

2, A switch of the class described, comprising a base, an operating tumbler, a rocking contact arm pivotally mounted in relation to the said base, a floating spring link connecting said tumbler to said contact arm, a spring confined to the link at a part thereof remote from its pivotal connection with the tumbler, and an abutment member mounted upon said base and presenting oscillation clearance for the contact arm and the link and abutment-tongues to'cooperate with the link for positively starting the contact arm during springstressing displacement of said tumbler.

3. A switch of the class described, comprising a base, an operating tumbler, a double-armed rocking contact member pivotally mounted upon said base, a floating link located between the arms of said rocking contact member and connecting said tumbler thereto, an abutment member mounted upon said base and having oscillation clearances for the sides of said rocking contact member and abutments adapted to impart positive start to said rocking contact arm during spring-stressing displacement of said tumbler, a thrust member pivotally mounted between the arms of said rocking contact member with which said link slidably engages, a thrust member located on said link at a distance from the end thereof connected to said tumbler, and a spring around said link, said spring being confined between said thrust members to enable said link to lever directly upon said abutments.

a. A switch of the class described, comprising a base, an operating tumbler, a double-armed rocking contact member pivotally mounted upon said base, a floating link located between the arms of said rocking contact member and connecting said tumbler thereto, an abutment member mounted upon said base and having clearances therein to permit of and limit the oscillation of said rocking contact and abutments intermediate said clearances adapted to impart positive start to said contact-arm during spring-stressing displacement of the said tumbler, a thrust member pivotally mounted between the arms of said rocking contact with which said link slidably engages, a thrust member located on said link at a distance from the end thereof connected to said tumbler, and a spring mounted around said link, said spring being confined between said thrust members to enable the end of the link adjacent the tumbler to lever directly upon said abutments.

5. A switch of the class described comprising a base, an operating tumbler, a double-armed rocking contact member, a pin secured to said base upon which said tumbler and rocking contact are pivotally mounted, a floating link located between the arms of said rocking contact and connecting said tumbler thereto, an abutment member mounted upon said base and having clearances thereon to permit of and limit the oscillation of said rocking contact and abutment: intermediate said clearances adapted to impart positive start to said rocking contact-arm when the said tum= bler is displaced to stress a spring, said pin being elevated in relation to said clearances, a thrust member pivotally mounted between the arms of said rocking contact with which said link slidably engages, a thrust member located on said link at a distance from its end thereof connected to said tumbler, and a spring mounted around said link and being confined between said thrusts to enable rot iii

the end of said link adjacent its connection with the tumbler to lever directly upon said abutments.

6. A switch of the class described, comprising a base, an operating tumbler, a double-armed rocking contact member, a pin upon which said tumbler and rocking contact are pivotally mounted, screws whose heads engage the extremities of said pin and secure it to said base, a floating link located between the arms of said rocking contact and connecting said tumbler thereto, an abutment member mounted upon said base and having clearances therein to permit of and limit the oscillation of said rocking contact and abutments intermediate said clearances adapted to impart positive start to said rocking contact arm when said tumbler is displaced to stress a spring, distance pieces located around said screws intermediate said abutment member and said pin to elevate the latter in relation to the former, a thrust member pivotally mounted between the arms of said rocking contact with which said link slidably engages, a thrust member located on said link at a distance from the end thereof connected to said tumbler, and a spring mounted around said link and confined between said thrust members to enable the end of said link adjacent its connection with the tumbler to lever directly upon said abutments.

7. A switch of the class described, comprising a base, an operating tumbler, a double-armed rocking contact member, a pin upon which said tumbler and rocking contact are pivotally mounted, screws whose heads engage the extremities of said pin and secure it to said base, a floating link located between the arms of said rocking contact and connecting said tumbler thereto, an abutment member mounted upon said base and having clearances therein to permit of and limit the oscillation of said rocking contact and abutments intermediate said clearances adapted to impart positive start to the contact arm when said tumbler is displaced in the spring-stressing direction, distance pieces located around said screws intermediate said abutment member and said pin to elevate the latter in relation to the former, a thrust member pivotally mounted between the arms of said rocking contact with which said link slidably engages, shoulders located on said link member at a distance from the end thereof connected to said tumbler, and a spring mounted around said link and confined between said thrust member and said shoulders to permit said shoulders to lever directly upon said abutments when the said tumbler is displaced.

JOHN ASHWORTH CRABTREE. 

